Question: What's the first wrong statement in the proof below that $ \triangle DEB \cong \triangle CEB$ $ \; ?$ $ \overline{BC} $ is parallel to $ \overline{DF} $. This diagram is not drawn to scale. $A$ $B$ $C$ $D$ $E$ $F$ Givens $ \overline{CF} \cong \overline{BD}$ $, \ $ $ \angle CFE \cong \angle DBE$ $, \ $ $ \overline{EF} \cong \overline{BE}$ $, \ $ $ \angle ABC \cong \angle DBE$ $, \ $ $ \overline{AB} \cong \overline{BE}$ $, \ $ and $\ $ $ \angle BAC \cong \angle BED$ Proof $ \triangle DEB \cong \triangle CEF$ because SAS $ \overline{DE} \cong \overline{CE}$ because corresponding parts of congruent triangles are congruent $ \overline{AF} \cong \overline{DE}$ because corresponding parts of congruent triangles are congruent $ \triangle DEB \cong \triangle CAB$ because ASA $ \angle BDE \cong \angle ACB$ because corresponding parts of congruent triangles are congruent $ \triangle DEB \cong \triangle CEB$ because SSS
Try going through the proof yourself: write down the givens, and then see if they justify the next step for the reason given. Then do the same thing for the next step, and the next, until you run into something that you can't justify, or you finish the proof. $ \overline{DE} \cong \overline{AF}$ is the first wrong statement.